Irene continues to weaken

By: Dr. Jeff Masters , 8:46 PM GMT on August 26, 2011

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Satellite data and measurements from the Hurricane Hunters show that Irene continues to weaken. A 1:32 pm EDT center fix by an Air Force Reserve aircraft found that Irene's eyewall is still gone, and the central pressure had risen to 951 mb from a low of 942 mb this morning. The winds measured in Irene near the surface support classifying it as a strong Category 1 hurricane or weak Category 2. Satellite imagery shows a distinctly lopsided appearance to Irene's cloud pattern, with not much heavy thunderstorm activity on the southwest side. This is due to moderate southwesterly wind shear of 10 - 20 knots. This shear is disrupting Irene's circulation and has cut off upper-level outflow along the south side of the hurricane. No eye is visible in satellite loops, but the storm's size is certainly impressive. Long range radar out of Wilmington, North Carolina, shows that the outermost spiral bands from Irene have moved ashore over North Carolina. Winds at buoy 41004 100 miles offshore from Charleston, SC increased to 47 mph, gusting to 60 mph at 3 pm EDT, with significant wave heights of 25 feet.


Figure 1. MODIS satellite image of Hurricane Irene taken at 11:50 am EDT Friday August 26, when Irene was a Category 2 hurricane with 105 mph winds. The eyewall collapsed several hours before this image was taken, and no eye is apparent. Image credit: a href=http://rapidfire.sci.gsfc.nasa.gov/gallery/ NASA.


Figure 2. Distribution of Irene's wind field at 3:30 pm EDT Friday August 26, 2011, as observed by the Hurricane Hunters and buoys. The right front quadrant of the hurricane had about 90% of the storm's hurricane-force winds (yellow and warmer colors, bounded by the heavy black line between the "50" and "60" knot thin black lines.) Tropical storm-force winds (heavy black like bounding the light blue area) extended out 290 miles from the center of Irene. Image credit: NOAA/AOML/HRD.

Forecast for Irene
With its eyewall collapsed and just 18 more hours over water before landfall, Irene does not have time to build a new eyewall and intensify. The storm is too large to weaken quickly, and the best forecast is that Irene will be a strong Category 1 hurricane at landfall in North Carolina on Saturday. Based on the latest wind analysis from NOAA's Hurricane Research Division (Figure 2) and Irene's continued weakening trend, I predict that the 80-mile section of North Carolina coast to the right of where Irene makes landfall will receive sustained hurricane-force winds of 75 - 85 mph on Saturday at landfall; the 80-mile section of coast to the left will receive 55 - 75 mph winds. High wind shear of 30 knots will begin ripping into Irene Sunday morning when it is near Southern New Jersey, and more rapid weakening will occur. By the time Irene arrives on Long Island Sunday afternoon, it will probably have top sustained winds in the 65 - 75 mph range. However, since Irene is such a huge storm--tropical storm force winds extend out up to 290 miles from the center--it has set a massive amount of the ocean's surface in motion, which will cause a much larger storm surge than the winds would suggest. At 3:30 pm EDT this afternoon, a wind analysis from NOAA/HRD (Figure 2) indicated that the potential storm surge damage from Irene still rated a 5.0 on a scale of 0 to 6. This is equivalent to the storm surge a typical Category 4 hurricane would have. While this damage potential should steadily decline as Irene moves northwards and weakens, we can still expect a storm surge one full Saffir-Simpson Category higher than Irene's winds when it impacts the coast. Since tides are at their highest levels of the month this weekend due to the new moon, storm surge flooding will be at a maximum during the high tidal cycles that will occur at 8 pm Saturday night and 8 am Sunday morning. Wherever Irene happens to be at those times, the storm surge damage potential will be maximized. I continue to give a 20% chance that a 3 - 4 foot storm surge high enough to over-top the Manhattan flood walls and swamp the New York City subway system will occur on Sunday. The latest 11 am probabilistic storm surge map from NHC shows a 20 - 30% chance of a storm surge in excess of 3 feet in New York Harbor (Figure 4.) Keep in mind that these maps are calculated for normal tide level, and this weekend's high tides will be nearly 1 foot above normal.

Insurance company AIR-Worldwide is estimating that insured damages from Irene in the U.S. will be $1.5 - $6 billion. They estimate losses in the Caribbean at $0.5 - $1.1 billion from Irene.


Figure 3. Storm surge heights, in feet above normal tide level, which have a 20 percent chance of being exceeded during the next 3 days.  The graphic is based upon an ensemble of Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model runs using the current National Hurricane Center (NHC) official hurricane advisory. The exceedance heights depend on the historical accuracy of NHCs forecasts of hurricane track, and wind speed, and an estimate of storm size. Image credit: NOAA.


Figure 4. Overall chance that storm surges will be greater than 3 feet above normal tide levels during the next 3 days.  The graphic is based upon an ensemble of Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model runs using the current National Hurricane Center (NHC) official hurricane advisory.  Storm surge probabilities depend on the historical accuracy of NHCs forecasts of hurricane track, and wind speed, and an estimate of storm size. Image credit: NOAA.

Links
For those of you wanting to know your odds of receiving hurricane force or tropical storm force winds, I recommend the NHC wind probability product.

Wunderground has detailed storm surge maps for the U.S. coast.

The National Hurricane Center's Interactive Storm Surge RIsk Map, which allows one to pick a particular Category hurricane and zoom in, is a good source of storm surge risk information.

Wunderblogger Mike Theiss is in Nassau, documenting the storm's impact on the Bahamas.

Internet radio show on Irene at 4:30pm EDT
Wunderground meteorologists will be discussing Hurricane Irene on a special edition of our Internet radio show, the Daily Downpour, today (Friday) at 4:30pm EDT. Shaun Tanner , Tim Roche, Angela Fritz, and Rob Carver will take your questions. The email address to ask questions is broadcast@wunderground.com.

Jeff Masters

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Quoting 996tt:


Yep. Great news. Turning into a perfect situation. I love riding out cat 1 or small cat 2 and just enjoying the force of mother nature without being scared out of my wits and having everything destroyed around me. Haha, if I wasn't surfing, I would load up car and drive to hang out in storm and surf OBX Sunday evening.


Let me remind you Ike was a Category 2 and Irene hase the IKE (not the storm) of a Category 3 hurricane. Oh yeah and Ike was one of the costliest to hit the U.S. ever. Don't be so blase when it comes to this storm. They've already reported flooding in Georgia and North Caroline and the storm isn't supposed to get there for another 18 hours or so. The East is going to be in for a wild ride even if it's "only" a Category 1 storm.
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IRENE COULD WEAKEN JUST BELOW HURRICANE STRENGTH BEFORE
REACHING SOUTHERN NEW ENGLAND.

This is great news.
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Quoting NICycloneChaser:
Looks like the pressure is dropping again...

Time: 21:36:00Z
Coordinates: 31.8N 77.2667W
Acft. Static Air Press: 752.7 mb (~ 22.23 inHg)
Acft. Geopotential Hgt: 2,046 meters (~ 6,713 feet)
Extrap. Sfc. Press: 948.7 mb (~ 28.02 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 42° at 9 knots (From the NE at ~ 10.3 mph)
Air Temp: 19.5°C (~ 67.1°F)
Dew Pt: 17.7°C (~ 63.9°F)
Peak (10s) Flt. Lvl. Wind: 12 knots (~ 13.8 mph)
SFMR Peak (10s) Sfc. Wind: 20 knots (~ 23.0 mph)
SFMR Rain Rate: 1 mm/hr (~ 0.04 in/hr)
(*) Denotes suspect data


Eh, not concerned with it. It dropped all day yesterday, and the winds went down. I'll start worrying when the winds being found get higher.
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Quoting TropicalAnalystwx13:
12Z ECMWF @ 144 hours:


is it gurranted the next storm recurves because the gfs in literally all of its runs recurves it
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Storm Relative 1km Geostationary Visible Imagery

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195. 996tt
Quoting wunderweatherman123:
just curious guys. next week 8 to 10 days what does the steering look to be. a out to sea pattern an east coast pattern or a gulf pattern?


On Monday and Tuesday, Irene was supposed to be GOM. Long term steering forecast just seem like a waste of breathe as no one really has a clue. That being said, GOM is blocked and EC has a target on its coast.
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May be strengthening again, latest cold cloud tops near the CDO is getting more noticeable on loops. This maybe her last hoorah before plowing into NC, then up the coast. Don't be relaxed since she's only 100mph now, don't be shocked to see her get back to 115mph
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Quoting QacarXan:
Is Irene going to re-form her eye? What are the odds?


Chances are low but far from impossible. With the way she looks now she's certainly running out of time to do so.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
12Z CMC @ 144 hours:

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Quoting violet312s:


Every image you posted came back with "Remote Linking Disabled" and a black box requesting to save the image and then upload it to a site like photobucket, etc. It's coming up that way for everyone linking to americanwx.com


As I noted. Don't have the patience to do all that work just for one image. Hope they find away around that issue.
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Radar is now showing the wedge of dry air in Irene.

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Quoting wunderweatherman123:
just curious guys. next week 8 to 10 days what does the steering look to be. a out to sea pattern an east coast pattern or a gulf pattern?


Gulf pattern
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And look the pattern on that 12Z GFS completely Zonal
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Quoting NICycloneChaser:
Looks like the pressure is dropping again...

Time: 21:36:00Z
Coordinates: 31.8N 77.2667W
Acft. Static Air Press: 752.7 mb (~ 22.23 inHg)
Acft. Geopotential Hgt: 2,046 meters (~ 6,713 feet)
Extrap. Sfc. Press: 948.7 mb (~ 28.02 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 42° at 9 knots (From the NE at ~ 10.3 mph)
Air Temp: 19.5°C (~ 67.1°F)
Dew Pt: 17.7°C (~ 63.9°F)
Peak (10s) Flt. Lvl. Wind: 12 knots (~ 13.8 mph)
SFMR Peak (10s) Sfc. Wind: 20 knots (~ 23.0 mph)
SFMR Rain Rate: 1 mm/hr (~ 0.04 in/hr)
(*) Denotes suspect data


Not good.
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Quoting HurricaneDean07:
Wow from the looks of it Beaufort, NC will be getting what i thought it would, A landfall...

Hurricane season going to get kicking even further now, Could see, according to the models, Katia or Lee in the next week or two... This is one Active season...


Need Jose first...
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Quoting atmosweather:


Excellent image showing the presence of a formative inner eyewall as RECON confirmed and then a secondary strong outer rainband around 80-90 miles from the center that is still trying wrestle control of the inner core.


Do you think Irene is starting to overcome the dry air..looks like it to me on satellite.
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This is good practice for the NE - look at the train behind Irene - TD10 and invest 91, not great looking for the NE
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Quoting CybrTeddy:
Hate to take it off topic from Irene.. but the models have been for over a day indicating that yet another significant hurricane will develop late next week. We saw this with Irene, and it could verify. Obviously, track isn't important atm.
12z GFS, 144 hours. Strong TS in the open Atlantic, develops on the 31st. Intensifies into a hurricane later in the run.


12z ECMWF, 144 hours. Also shows a TS in the open Atlantic, intensifies into a Category 4 hurricane later in the run. Also worth noting that both the ECMWF and NOGAPS show a TS or hurricane in the BOC hitting Mexico. Looks like a Hermine situation if that verifies.


12z GGEM/CMC. Same as the ECMWF/GFS, probably a hurricane later in the run.


12z NOGAPS, TS in 144 hours, system in the BOC.


The name game isn't over yet after Irene.. more and more storms to come. We're not even at peak yet, that's not for two weeks.

19-20 named storms seems like a real possibility.


Every image you posted came back with "Remote Linking Disabled" and a black box requesting to save the image and then upload it to a site like photobucket, etc. It's coming up that way for everyone linking to americanwx.com
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Looks like the pressure is dropping again...

Time: 21:36:00Z
Coordinates: 31.8N 77.2667W
Acft. Static Air Press: 752.7 mb (~ 22.23 inHg)
Acft. Geopotential Hgt: 2,046 meters (~ 6,713 feet)
Extrap. Sfc. Press: 948.7 mb (~ 28.02 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 42° at 9 knots (From the NE at ~ 10.3 mph)
Air Temp: 19.5°C (~ 67.1°F)
Dew Pt: 17.7°C (~ 63.9°F)
Peak (10s) Flt. Lvl. Wind: 12 knots (~ 13.8 mph)
SFMR Peak (10s) Sfc. Wind: 20 knots (~ 23.0 mph)
SFMR Rain Rate: 1 mm/hr (~ 0.04 in/hr)
(*) Denotes suspect data
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Quoting WeatherNerdPR:

What, did you skip Jose?


In Texas Jose is a dime a dozen.....:>)
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Quoting Patrap:
AMSU Microwave 89GHz Imagery (4 km Mercator)



Excellent image showing the presence of a formative inner eyewall as RECON confirmed and then a secondary strong outer rainband around 80-90 miles from the center that is still trying wrestle control of the inner core.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
just curious guys. next week 8 to 10 days what does the steering look to be. a out to sea pattern an east coast pattern or a gulf pattern?
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12Z ECMWF @ 144 hours:

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177. 996tt
Quoting Levi32:


If she continues to look this way over the next 3-6 hours I would agree completely with the NHC forecast, though there is still an outside chance of some reorganization. This is definitely good news for North Carolina though. Hopefully they will get off alright tonight, but it will be rough. I just saw a clip of waves already crashing through the tops of dock pilings on a beach in NC...could see some of those collapse later tonight.


Yep. Great news. Turning into a perfect situation. I love riding out cat 1 or small cat 2 and just enjoying the force of mother nature without being scared out of my wits and having everything destroyed around me. Haha, if I wasn't surfing, I would load up car and drive to hang out in storm and surf OBX Sunday evening.
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Does anyone have any good links to webcams near the area were the hurricane is projected to hit? thanks
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Power still out at Folly?
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Quoting Levi32:
Even now, Irene's pressure doesn't want to rise much, and is down 1mb from before. This is a testament to the overall pattern in this area of the world which has argued for a big storm. For all of her troubles with her inner core, Irene will want to remain a strong storm as she moves up the coast, and folks should not take her lightly.

Indications from recon wind data are that if she's going to form even a partial new eyewall, it should be about 30 miles across, as that is where the wind maxima begin.


you are 100 percent correct , the eye wall might not be full but this storm is acting different then normal canes..this is good because areas north (from its current point)will not get beat up..BUT it will be a storm that all in the area should be very aware of....
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Dry air seems to really be kicking the steam out of Irene.


I'd be surprised if it wasn't downgraded later today.
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Quoting HurricaneDean07:
Wow from the looks of it Beaufort, NC will be getting what i thought it would, A landfall...

Hurricane season going to get kicking even further now, Could see, according to the models, Katia or Lee in the next week or two... This is one Active season...

What, did you skip Jose?
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There is always a way around those things CybrTeddy ;)



12Z GFS @ 144 hours.
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Thanks Randy!
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Cool app on iTunes for tracking the Hurricane Hunters


http://itunes.apple.com/us/app/hurricanehunterapp colallc/id456831217?mt=8
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Is Irene going to re-form her eye? What are the odds?
Member Since: August 25, 2011 Posts: 0 Comments: 20
Quoting TropicalAnalystwx13:
I live here (the little red dot):



Oh wow. Yup, you're definitely in for a long night. Stay safe!
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Wow from the looks of it Beaufort, NC will be getting what i thought it would, A landfall...

Hurricane season going to get kicking even further now, Could see, according to the models, Katia or Lee in the next week or two... This is one Active season...
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AMSU Microwave 89GHz Imagery (4 km Mercator)

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5:34 PM 75.2 °F - 73.4 °F 94% 29.64 in 3.0 mi ENE 27.6 mph 42.6 mph 0.09 in Rain Heavy Rain

WILMINGTON
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whoa anyone notice 91 invest poppin up.
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Who's in charge here?!
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Quoting CybrTeddy:


Your kidding me?? They removed linking from that site? Unbelievable.


Yeah that only just happened...its a joke.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
Quoting wunderweatherman123:

she isnt looking too hot right now. do you agree with what the nhc is forecasting, a cat 1 at landfall in NC? i personally dont as her pressure doesnt rise that much anymore. i see her making landfall as a cat 2


If she continues to look this way over the next 3-6 hours I would agree completely with the NHC forecast, though there is still an outside chance of some reorganization. This is definitely good news for North Carolina though. Hopefully they will get off alright tonight, but it will be rough. I just saw a clip of waves already crashing through the tops of dock pilings on a beach in NC...could see some of those collapse later tonight.
Member Since: November 24, 2005 Posts: 635 Comments: 26547
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Storm Relative 1km Geostationary Visible Imagery

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Quoting atmosweather:


Winds at the top of high rise buildings and skyscrapers will be about 1 Category higher than the maximum surface winds.


That's interesting to know.
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153. 996tt
Quoting victoriahurricane:
Does anyone have a link to a webcam with sound showing Irene's waves at a beach somewhere close to landfall expectations?


That was the best thing about monitoring Ike. W3e had all of those web cams to views on Galviston Beach area.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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